Field of the Invention
The present invention relates to density adjustment control.
Description of the Related Art
An electrophotographic image forming apparatus forms an electrostatic latent image on a photosensitive member based on image data, and develops the electrostatic latent image using developer in a development device to thereby form an image. The development device frictionally charges the developer in the development device to thereby change the charge amount of the developer. It is known that a density of an image formed by an image forming apparatus changes depending on the charge amount of developer in a development device. When the charge amount of the developer decreases, the density of the image formed by the image forming apparatus becomes higher. On the other hand, when the charge amount of the developer increases, the density of the image formed by the image forming apparatus becomes lower.
It is important for the electrophotographic image forming apparatus to control the charge amount of the developer in the development device to be a target value in order to form an image with a desired density. However, when, for example, the image forming apparatus forms a plurality of images at low toner consumption, the consumed developer is slight and the developer contained in the development device thus can be excessively charged.
Therefore, when the charge amount of developer increases due to an image having been formed at low toner consumption, an image forming apparatus described in Japanese Patent Application Laid-Open No. 2003-263027 forcibly discharges the developer to thereby decrease the charge amount of the developer contained in a development device. The image forming apparatus forms an electrostatic latent image in an area where, on a photosensitive member, an image is not formed, and develops the electrostatic latent image by use of the developer to thereby form a pattern image which is to be used for discharging the developer. The pattern image is not transferred onto a recording material but is cleaned by a cleaning member. Even when the charge amount of the developer in the development device excessively increases, the image forming apparatus can decrease the amount of the developer in the development device by forming a pattern image and discharging the developer, and further can decrease the charge amount of the developer in the development device due to new toner supplied to the development device.